翻訳と辞書 Words near each other ・ Hazard Center (San Diego Trolley station) ・ Hazard Communication Standard ・ Hazard Community and Technical College ・ Hazard E. Reeves ・ Hazard family ・ Hazard Farmstead (Joyner Site RI-706) ・ Hazard H. Sheldon House ・ Hazard High School ・ Hazard map ・ Hazard mitigation in the Outer Banks ・ Hazard Park ・ Hazard Pay ・ Hazard Perception Test ・ Hazard pointer ・ Hazard quotient ・ Hazard ratio ・ Hazard Rock ・ Hazard Stevens ・ Hazard symbol ・ Hazard's Pavilion ・ Hazard, Kentucky ・ Hazard, Nebraska ・ Hazardia ・ Hazardia (plant) ・ Hazardia berberidis ・ Hazardia brickellioides ・ Hazardia cana ・ Hazardia detonsa ・ Hazardia ferrisiae ・ Hazardia orcuttii Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Hazard ratio ： ウィキペディア英語版 Hazard ratio In survival analysis, the hazard ratio (HR) is the ratio of the hazard rates corresponding to the conditions described by two levels of an explanatory variable. For example, in a drug study, the treated population may die at twice the rate per unit time as the control population. The hazard ratio would be 2, indicating higher hazard of death from the treatment. Or in another study, men receiving the same treatment may suffer a certain complication ten times more frequently per unit time than women, giving a hazard ratio of 10. Hazard ratios differ from relative risks in that the latter are cumulative over an entire study, using a defined endpoint, while the former represent instantaneous risk over the study time period, or some subset thereof. Hazard ratios suffer somewhat less from selection bias with respect to the endpoints chosen and can indicate risks that happen before the endpoint. ==Definition and derivation== Regression models are used to obtain hazard ratios and their confidence intervals. The instantaneous hazard rate is the limit of the number of events per unit time divided by the number at risk, as the time interval approaches 0. ::$h(t)\; =\; \backslash lim\_\backslash frac$ where ''N''(''t'') is the number at risk at the beginning of an interval. A hazard is the probability that a patient fails between $t$ and $t+\backslash Delta\; t$, given that he has survived up to time $t$, divided by $\backslash Delta\; t$, as $\backslash Delta\; t$ approaches zero.〔 The hazard ratio is the effect on this hazard rate of a difference, such as group membership (for example, treatment or control, male or female), as estimated by regression models that treat the log of the HR as a function of a baseline hazard $h\_0(t)$ and a linear combination of explanatory variables: ::$\backslash log\; h(t)\; =\; f(h\_0(t),\backslash alpha\; +\; \backslash beta\_1\; X\_1\; +\; \backslash cdots\; +\; \backslash beta\_k\; X\_k).\backslash ,$ Such models are generally classed proportional hazards regression models; the best known being the Cox semiparametric proportional hazards model,〔 and the exponential, Gompertz and Weibull parametric models. For two groups that differ only in treatment condition, the ratio of the hazard functions is given by $e^\backslash beta$, where $\backslash beta$ is the estimate of treatment effect derived from the regression model. This hazard ratio, that is, the ratio between the predicted hazard for a member of one group and that for a member of the other group, is given by holding everything else constant, i.e. assuming proportionality of the hazard functions.〔 For a continuous explanatory variable, the same interpretation applies to a unit difference. Other HR models have different formulations and the interpretation of the parameter estimates differs accordingly. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hazard ratio」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.